This invention relates to an open-close device for disposal between a main body containing therein an opening and an open-close member capable of closing the aforementioned opening, for attaching the open-close member to the main body so as to be operable to open and close the opening.
As one typical example of prior art, there may be cited Japanese Utility Model Examined Publication No. 49(1974)/47567 which discloses a metallic open-close device formed of two pairs of movable members pantographically assembled by having one of the pairs of movable members pivotally fastened with pins at spaced locations to a first base plate secured to an inner surface of a main body, the other pair of movable members pivotally fastened with pins at spaced locations to a second base plate secured to a lid serving as an open-close member, the free ends of the movable members of one pair pivotally fastened with pins to the free ends of the corresponding movable members of the other pair, and the mutually crossing movable members, one from each of the two pairs, pivotally fastened to each other with a pin at the point of intersection thereof.
This metallic open-close device of the prior art is formed of two base plates and four movable members and assembled by use of seven pins. Since the number of component parts is very large, the work of assembling this device entails much time and labor. Further within this pantographic mechanism, there is separately incorporated a spring plunger unit which assumes the most compressed state at the medial length of its expansion or contraction and manifests its resiliency during its expansion or contraction past the aforementioned medial length. Thus, the spring plunger unit enables the device to produce a quickened motion during its operation.
An arrangement wherein the lid is normally locked in its closed state by means of a lock provided at the free end of the lid and, when necessary, the lid is automatically opened completely or partially by releasing the lock can not be accomplished with the aforementioned spring plunger unit. In any event, in the conventional pantographic open-close device, a movement making use of resiliency cannot be produced unless the device separately incorporates therein spring means. This inconvenience is similarly experienced by the open-close device disclosed in Japanese Utility Model Unexamined Publication No. 52(1977)/77376.
An object of this invention is to provide an open-close device which comprises only few parts molded of a plastic substance and, therefore, is capable of easy assemblage.
Another object of this invention is to provide a pantographic open-close device which is adapted so that an open-close member (the lid) is brought into its locked position to close the opening in the main body by contraction of the pantographic mechanism and the open-close member is brought into its completely or partially opened state by releasing the lock and consequently allowing the pantographic mechanism to expand automatically.